Define relative risk and absolute risk in epidemiology and explain how they guide public health decisions.

• A. Absolute risk is the ratio of risk in exposed to unexposed; relative risk is the probability of an event in the population; used to monitor changes over time.
• B. Absolute risk is the probability of an event in a population; relative risk compares risk between exposed and unexposed groups; used to identify effective vaccines.
• C. Absolute risk is the probability of an event in a population; relative risk compares risk between exposed and unexposed groups; used solely to determine etiologic fractions, not to prioritize interventions.
• D. Absolute risk is the probability of an event in a population; relative risk compares risk between exposed and unexposed groups; used to assess strength of associations and prioritize interventions.

Answer: (D)